What is Calendar-Time Portfolio

While the authors has a clear preference for an event study that estimates the short-run calculations of abnormal stock returns over a short multi-day window, there are other forms that readers should be familiar with. Further, you should be aware of the challenges of conducting and interpreting these studies. Therefore, this chapter addresses long-run studies and some difficulties, criticisms, and interpretation issues of using these studies. Finally, it looks at studies that do not use abnormal stock returns but use changes in operational data. Using these alternatives can enable a project to extend its contribution by using several studies (e.g., both short- and long-run studies) in one journal article or dissertation to converge on insights into the phenomenon being studied.